Governor assemblies

ABSTRACT

A rotatable governor assembly which includes an epicyclic gear to impart to the governor spring a rotation opposite in direction and equal in speed to that of the bobweights so that the governor spring remains stationary relative to earth.

United States Patent [191 McMurtry GOVERNOR ASSEMBLIES David Roberts McMurtry, 21 Stoney Stile Road, Alveston. England Filed: May 3, 1972 Appl. No.: 250,044

Inventor:

[30] Foreign Application Priority Data May 15, 1971 Great Britain 15,184/71 521 U.S.Cl. 73/535, 73/550 511 lnt.Cl. G01p3/16,G05d 13/12 58 FieldofSearch 73/494, 535, 550;

[56] References Cited UNITED STATES PATENTS j 3.251.373 5/1966 Drake 73/535 X Primary Examiner-James J. Gill Attorney-Richard K. Stevens et a].

[5 7] ABSTRACT A rotatable governor assembly which includes an epicyclic gear to impart to the governor spring a rotation .opposite in direction and equal in speed to that of the bobweights so that the governor spring remains stationary relative to earth.

10 Claims, 1 Drawing Figure e4 32 M 16 37 1.1 33 73 1 2 s r 36 72 \3 I l8 :J

GOVERNOR ASSEMBLIES The present invention relates to a rotatable governor assembly. 1

According to the present invention there is provided a rotatable governor assembly comprising a body having centrifugally moveable bobweights connected thereto, a governor spring connected for spring urging the bobweights, and means for imparting to the spring a rotation opposite in direction and substantially equal in speed to that of the bobweights when the assembly is rotated.

In a preferred form of the invention said means is a differential gear which is connected to the spring.

An envisaged application of a rotatable governor assembly according to the invention is as part of a control system for a variable pitch fan or propeller. The control system which is completely self-contained and in the form ofa module contained within a casing can be connected to the fan or propeller rotor to rotate therewith as a single unit. Within the casing are provided an oil tank, an oil pump, a pitch-change mechanism and governor for controlling the fan.

One problem of the self-contained control system is that as it rotates with the fan or propeller there is no stationary structure on which to attach the governor body and it has been found that the spring ofa centrifugal governor varies in rate if made to rotate and no longer provides accurate governing. The present invention overcomes this problem.

An embodiment ofa rotatable governor assembly according to the invention will now be described, by way of example only, with reference to the accompanying drawing which shows an axial section of:

A rotatable governor assembly 11 rotatably mounted in, and coaxial with the axis of rotation of, a rotatable housing 12 from ball and roller bearings 13 and 14 respectively and lands l and 16. The bearings 13 and 14 are located in a bearing housing 17 which is integral with the housing 12. The lands l5 and 16 are part ofa spool 22 and bear against the walls of a cylindrical bore 18 in the housing 12.

The housing 12 comprises cylindrical portions 60 and 61 bolted together by means of nut and bolt assemblies 62, and a cylindrical shaped block 63 in nesting relationship with the portion 61. The block 63 includes passages 64 and 65 therein for the supply of oil therethrough to and from the cylindrical bore 18 via ports 41 and 42 respectively.

The governor assembly 11 comprises bobweights 21 pivotally mounted from the housing, a spool 22 which is in axial alignment with and held from a stub shaft 23 of a bevel gear 24 by a straight coiled spring 25. The spool 22 and stub shaft 23 are rotatably connected by a linkage system 26 to allow relative axial movement therebetween.

The bevel gear 24 forms part of an epicyclic bevel gear train 27 which also comprises a first bevel gear 28 and a second bevel gear 29. The gear 28 is mounted from and rotated by a first external drive (not shown) and meshes with the second gear 29 which is rotatably mounted from the housing 12 on hearing 50 and connected to an accessory drive shaft 31. The gear 29 meshes with the bevel gear 24.

The housing 12 is provided with a radially extending flange 30 and is rotatably connected at the flange to a second external drive (not shown). The respective rotations imparted by the firstand second external drives are in the same direction and in constant speed ratio. The gear teeth ratios of the gears 24, 29 and 28 are so designed that when the gear 28 is rotated by the first external drive and the housing 12 is rotated by the sec ond external drive the rotation imparted to the gear 24, and hence the spring 25 and the spool 22, is opposite in direction and substantially equal in'speed to that of the housing 12, hence the rotation of the governor assembly is substantially zero relative to earth.

Each bobweight 21 pivots about a pin 32 and is provided with a bell-crank arm 33 the outer end of which engages in a circumferential groove 34 in a collar 35 which is rotatably mounted around the spool 22 from a bearing 36.

Between the lands 15 and 16 and the spool and the walls of the cylindrical bore 18 is formed an annular channel 37 open to the oil supply port 41. The land 15 seals the port 42 in the wall of the cylindrical bore 18.

In operation as the housing 12 is rotated and each bobweight 21 pivots under centrifugal force the bellcrank arm moves the collar and the spool in an axial direction to compress the spring 25 and at a given speed to give flow connection between the channel 37 and the port 42 through which oil flows to the pitch change mechanism (not shown). Since the rotation of the governor assembly remains substantially zero relative to earth the spring is not subjected to centrifugal force. When the speed of rotation of the housing falls below the given speed the spool 22 returns under the spring load to the position where the land 15 seals the port 42. The rotation of the spool 22 relative to the housing 12 facilitates an easier axial sliding movement of the spool in the cylindrical bore 18.

The spring 25 is mounted from each end in cupshaped collars 52 and 71 respectively.

The collar 71 is mounted on the spool valve 22 and is in splined engagement therewith by means of splines 72 and is locked in one position on the spool valve by means of a lock washer 73.

The collar 52 is mounted on the stub shaft 23 and is in splined engagement therewith by means of splines 59. A thrust bearing 58 is mounted on the collar 52 and includes a lug S6 projecting from its outer race 57. The

lug 56 is pivotally connected by means of a pin 55 to a control rod 54. The control rod 54 is actuated from an external source (not shown) to slide the collar 52 in an axial direction relative to the stub shaft 23 to a position where a desired spring load is obtained and then to hold the collar 52 in said desired position. The spring load of the spring 25 will determine the speed of rotation at which the bobweights cause the spool valve 22 to move towards the stub shaft against the spring load and to give open connection between the annular channel 37 and the port 42.

The linkage system 26 comprises a pair of plates 43,44 pivotally connected one to the other by a pin 45 and respectively pivotally connected to the collars 71 and 52.

I claim:

1. A governor assembly and a first drive means for rotating the governorassembly about the longitudinal axis of the assembly, said governor assembly comprising a casing having mounted therein centrifugally movable bobweights pivotally connected from the casing, and a governor spring which is disposed in the casing for spring urging the bobweights, wherein the improvement comprises a second drive means for imparting to the governor spring a rotation which is opposite in direction and substantially equal in speed relative to that imparted to the governor spring by the first means so that the resultant rotation of the governor spring is substantially zero relative to earth.

2. A governor assembly as claimed in claim 1 in which said second drive means for imparting a rotation to the governor spring comprises a differential gear which is drivingly connected to the governor spring.

3. A governor assembly as claimed in claim 2 in which the governor assembly comprises also a spool valve and a stub shaft of the differential gear rotatably connected together by a linkage system, said stub shaft being rigidly connected to a gear wheel of the differential gear.

4. A governor assembly as claimed in claim 3 in which said governor spring is disposed between and connected to the spool valve and the stub shaft.

5. A governor assembly as claimed in claim 4 in which the spool valve, the governor spring and the stub shaft are in a coaxial relationship.

6. A governor assembly as claimed in claim 5 in which the spool valve, the governor spring and the stub shaft are rotatable by said second drive means.

7. A governor assembly as claimed in claim 6 in which each bobweight comprises a bell-crank arm connected to the spool valve to produce, during rotation of the governor assembly about its longitudinal axis, a movement of the spool valve against the action of the governor spring.

8. A governor assembly as claimed in claim 7 in which the bell-crank arm of each bobweight is connected to the spool valve by engaging with a first collar which is rotatably mounted around the spool valve from a bearing which is in turn mounted on the spool valve.

9. A governor assembly as claimed in claim 8 in which adjustable means are provided to set the governor spring to a predetermined length such that, in operation of the governor assembly, said predetermined length of the governor spring will determine the speed of rotation of the governor assembly at which the bobweights will begin to move the spool valve against the action of the governor spring.

10. A rotatable governor assembly as claimed in claim Q in which the adjustable means comprises a second collar mounted on the stub shaft and in sliding engagement therewith, said second collar abutting an end coil of the governor spring and capable of being moved along the stub shaft to a desired position and held thereat by means of an externally controlled rod which is pivotally connected to the outer race of a bearing which is mounted on the second collar. 

1. A governor assembly and a first drive means for rotating the governor assembly about the longitudinal axis of the assembly, said governor assembly comprising a casing having mounted therein centrifugally movable bobweights pivotally connected from the casing, and a governor spring which is disposed in the casing for spring urging the bobweights, wherein the improvement comprises a second drive means for imparting to the governor spring a rotation which is opposite in direction and substantially equal in speed relative to that imparted to the governor spring by the first means so that the resultant rotation of the governor spring is substantially zero relative to earth.
 2. A governor assembly as claimed in claim 1 in which said second drive means for imparting a rotation to the governor spring comprises a differential gear which is drivingly connected to the governor spring.
 3. A governor assembly as claimed in claim 2 in which the governor assembly comprises also a spool valve and a stub shaft of the differential gear rotatably connected together by a linKage system, said stub shaft being rigidly connected to a gear wheel of the differential gear.
 4. A governor assembly as claimed in claim 3 in which said governor spring is disposed between and connected to the spool valve and the stub shaft.
 5. A governor assembly as claimed in claim 4 in which the spool valve, the governor spring and the stub shaft are in a coaxial relationship.
 6. A governor assembly as claimed in claim 5 in which the spool valve, the governor spring and the stub shaft are rotatable by said second drive means.
 7. A governor assembly as claimed in claim 6 in which each bobweight comprises a bell-crank arm connected to the spool valve to produce, during rotation of the governor assembly about its longitudinal axis, a movement of the spool valve against the action of the governor spring.
 8. A governor assembly as claimed in claim 7 in which the bell-crank arm of each bobweight is connected to the spool valve by engaging with a first collar which is rotatably mounted around the spool valve from a bearing which is in turn mounted on the spool valve.
 9. A governor assembly as claimed in claim 8 in which adjustable means are provided to set the governor spring to a predetermined length such that, in operation of the governor assembly, said predetermined length of the governor spring will determine the speed of rotation of the governor assembly at which the bobweights will begin to move the spool valve against the action of the governor spring.
 10. A rotatable governor assembly as claimed in claim 9 in which the adjustable means comprises a second collar mounted on the stub shaft and in sliding engagement therewith, said second collar abutting an end coil of the governor spring and capable of being moved along the stub shaft to a desired position and held thereat by means of an externally controlled rod which is pivotally connected to the outer race of a bearing which is mounted on the second collar. 